DE 10 2005 102 404 B4 discloses a circuit board having a first, a second and a third rigid region and a first and a second flexible region. The flexible regions are made thinner than the rigid regions perpendicularly to the sides of the circuit board, wherein the flexible regions are formed by depth milling of the circuit board. The flexible region comprises a layer for conductor tracks, a protective layer above the layer for conductor tracks, and a residual layer of circuit board material on a side of the layer for conductor tracks which is opposite to the protective layer.
The flexibility of the flexible region is restricted by the circuit board material conventionally used.
WO 2007/064138 A1 discloses a circuit board having a first and a second part, wherein a depression is arranged between the first and second parts. A metal layer is applied on the surface of the circuit board by means of a sputtering process.
DE 44 05 228 C1 and WO 2005/033787 A1 likewise disclose circuit boards having a plurality of sections, wherein at least one section has a depression.